Microphonic apparatus



Patented Oct. 3, 19.3 9

UNITED 'sTATEs PATENT j :OFFICE Mlciornomc APPARATUS Thomas B'. Gibbs, chicago, m. Applieation February 8, 1937, Serial No. 124,570 1s claims. (cl'. 'is-'sly My invention relates in general to microphones,

and more'in particular to a' device of this character which is `adapted for use in connection with :watch timing apparatus for converting the' me- -chanical vibrations produced by the ticking of a watch into electrical impulses. invention are to produce a new and improved microphone which is suitable for the foregoing and similar purposes, and to'provide necessary and desirable auxiliary arrangements whereby the microphone may beincorporated into a watch timing system.

The invention will be described hereinafterA with reference to the accompanying drawing, in

.'25 Referring to the drawing, Fig. 1 shows a stand comprising a base 2. an upright rear portionA or back 3, andthe sides 4 and 5 with sloping front edges, as shown. The stand may be formed of sheet metal suitably embossed or otherwise n- The arrangement of the stand is such as toform microphone is tuus ily accessible.

As shown in Fig. l, the microphone has a casing l ior enclosingthe parts landfa cover .plate Il.

The latter has on its upper, surface a layer of felt position bysuitable clamping means. Thisarrangement comprises amenber I3 secured to the cover plate I l by screws (see Fig. 2) sind a clamp- '45 ing screw I4.

-The means for supportingthei'nicrophone case ing on the stand is partly shown in Fig. l, but may be understood more clearly from Fig. 2.l There is an opening in casing I0 on theright, as seen Jin Fig. 2, and surrounding this openingthere is a cylindrical collar. I5, suitably secured' to the ca'sing, as by soldering. This' collar I5 aiords means for rigidly attaching to the casing a tubelB which enters the opening in casing, and whichserves as a conduit for the microphone'connecting cord The objects of the ished to present a neat and attractive appearance.'

a partial enclosure within which the microphone is mounted against the bagk of thestand.. The

somewhat protected' from 35 accidental damages and at the same time .is read- '-1 I2 on which a watch may be placed and held in and also as a rotatable shaft by which the microphone is adjustably supported.

The upright rear portion 3`of the'stand includes Afront and back walls spaced apart, and the front wall I1 hasan opening therein to receive the tube 5 or conduit I G. The tubel I6 is rotatably secured to the wall 1 by an arrangement which .will now be explained, reference being made especially to Fig. 2. 'Surrounding' the openingin Wall I1 are tworubber gaskets or washers I8 and I9,.one on l@ each side of the wal1, and extending through these washers and the opening in the Wall is'a rubber bushing 2U. There is also provideda sleeve member 2|, having a head ,portion and a shank portion threaded at the end. 'rhoA shank of the 15 member 2l is positioned within the bushing 20, with the head against the bushing and the washer I9, there being, however, an.,v interposed metal washer 22. A similar washer 23 is inserted under the nut 24, by means of which 'member 2I is held 20 in place.

The 'tube I6 passes through a central longitudinal opening in the member 2l and is rotatable therein, suitable friction means being provided, however.' to oppose rotation so that-the micro- 25 phonewill remain in any position t0 which it l5 turned. vThis means comprises a cup-shaped washer 25, a flat resilient washer 26, and a nut 21. 'I'he latter Ais threaded on the end of the tube I6, after thewashers areput in p lace. When the nut 30 2l is tightened, the collar I5'is drawn up against the head of member 21 and further tightening of the nut bendsl the resilient washerf26. The n ut is adjusted so that the desiredamount of friction is deveioped.- The parts just described au ne in the 35 fcom'partment formed bythe front and rear walls -ofthe upright .rear portion l3 of the stand. The

rear wall (not shown) is preferably in the form of a removable cover plate. and may be provided with a suitable hushed opening thrcugh whionthe cord. 40

passes.

The so-called crystal which-constitutes the operative element of themicrophoe comprises two squareA sheets or plates 35 and 3 1 of Rochellesalt, 146 cemented together with a layerof foil 36 betweenv them. There is also a layer of `foil 3' 4 on one side and a layer of4 foil 38 on the other. Thereis a thin strip of brass 40 assembled next to the f oil 36,

and underneath the foils 38 and 34- are assembled 5o thin brass strips 4| aimiez,- respeotively.. The' brass strips 4I and 42 are direct1y opposite one another, and their ends are brought together and are soldered to terminal strip'la. .-The strip 40 is soldered to terminal strip 44. At one cornerof n the assembled crystal there-is cemented a member 39, to which is attached a short' pin or rod 45..

The. crystal is containedin a sealed receptacle comprising metal plates 36 and 33 and rubber lextends outside the-receptacle through an opening in plate 30, this opening being provided with a soft l 'rubber bushing which surrounds pin 45. The remeans of screw 6I.

ceptacle with the -crystal containedtherein is subjected to compression after being assembled, and the plates 30 and 33 are thenv secured together by` four tubular rivets, suchas 41 and 48.

Thus the terminal strips 43 and 44 are held tightly between rings 3| and 32, and the crystal is supportedgat lthree corners by the blocks 46, which are com-f,-

pressed betweenplates 30 and 33.

The unit is securely held to thecover plate II by two screws 55 and' 55', spaced 180 apart. These screws are shown in section in Fig. 3, and screw 55 appears in Fig( 2. The screws pass through two of the tubular rivets, such as 41, and are threaded into the cover plate.' Washers, such as 53, are provided to space the unit slightly away from the cover plate.

As shown in Figs. 2 and 4, there is a recess cut in the lower side of -the cover plate I I, in which is positioned a light spring member 60. This spring is secured at one end to the cover plate II by When the cover plate and crystal unit are assembled, as described in the preceding paragraph, the pin 45 passes through a small hole in the end of spring`60. The cover plate I I is provided with an' opening 62 just above the end of spring 60, which is large enough to.

enable pin `45to be secured to the end of the spring by soldering:--After this is done, the'pning is closed by a small-metal disc 65. 'I'he layer of felt I2, of course, is not put in place until after the other parts are assembled. It may be at'- tached with glue or .she1lac. The actuating pin '64 is attached to spring 60 andV extends up through an opening 63 in the'cover plate I I and v'through a hole in the felt I2. The top of the pin face of the cover plate. The assembly is held in l Surface of the felt;

The manner in which the cover plate and crystal unitare assembled in the casing I0 may now 64 may be just slightly higher than'the upper be explained. vAssuming the latter has already4 been mounted on the stand, the cord may be pulled through the tube I6 far enough so that it can easily be attached. 'to the terminals 43 and 44. As shown herein, -the cord comprises an Vinsulatedconductor 1I, surrounded lby 'a woven metal sheathing 50, over which may bea layer-of rubberl insulation 12. The` conductor 1I issol.` dered to the terminal 44, and the metal sheathing A50 is soldered to the terminal 43. The rubber insulation 12 may iirst beremoved for. several inches so as to eggpose the sheath 50.

`After.. theco'd has been attached, it may he pulled back, while the assembled crystal unit and cover plate. are placed in position, with the rim 'of the casing entering the groove in the lower surthe casing by two screws 56 and 56I shown in section in Fig. 3, from which the position of these-A screws relative to each other and tos'crews 55 'Ihere is an opening 14 in tube I6, which lies. be-

tween the washer v25 and the washer 26, and which is fully exposed by the-temporary removal of'these washers and nut 21. The sheath 50 can 15 thus be rmly soldered'to the tube I6,'after which the washers and nut are replaced. The soldered connection not only serves to conductiv'ely connect the tube and casing with themetal sheath of the cord, butit also serves to hold the latter 20 in place in the tube I6 and eliminates any danger of breaking the terminal connections. f

For convenience in connecting up the microphone,v.the cord is preferably terminated in a plug, which may be of the type shown in the 25 drawing.` This plug comprises a sleeve member A 13, a tip member 14', and a thimble 15. 'I'he latter, although frequently made of insulating material, should in this case be of metal. Thevconductor 1I is connected to the tip of the plug, and 30 the sheath 50 is soldered to'the sleeve, al1 as clearly shown. It will be noted that the construction shown provides for a complete shielding of one side of the microphone circuit, from .central foil36 of theAcrystal element to the ex- 35 treme tip of the plug.

The operation of the device may now be described. For this purpose it will be assumed that the microphone is connected by means of the cord and plug to an amplifier, which may form part ,lo of a watch timing' apparatus.

A watch may now be placed on the microphone, resting on the felt I2, and the clamping screw I4 may be turned down enough to hold the watch in position. The lower side of the. watch case 45 presses on the end of pin 64, which isdepressed a little, and spring 60 is slightly tensioned.

Assuming that the watch is running, at each tick a slight mechanical shock will be .transmitted through the case to the pin 64, and by way of 50 vnal crystal and areso related to eachother in the 55 assembly `that amovement of the free corner in a direction perpendicular'to the crystal faces, such as is produced by the shock ofthe watch tick, will generate a. voltage between the inner foil 36 andftheouter foils 34 and 38. This voltage `is 60 transmitted 4through terminals 43 -and .44 and through the cord and plug to the amplifier. The watch. may be tested in various positions,

as is generally required. For instance, it will be y 4clear enough that.the -watch can be placed on the '55 microphone with the face up or with the -face down, and" in either position can be rotated around a perpendicular axis passing throughi'tlie clampng screw I4. vIn order'. to test the watch I in an upright Xposition, as it is carried inthe 70 pocket, the microphone is rotated in either direction,'the clamping-screw -I4fhaving been tightened up enough to prevent the watchfrom slipping o. When the microphone is rotated,

the'tube or shaft I6 turns in the sleeve member 'Il adjusted because of thel frictional means including the resilient-washer 26.

The impulses generated by the crystal .are ofA uniform amplitude regardless of the position of the microphone, and are not mixed with inter fering impulses, suchas might begenerated by extraneous vibrations, mechanical, acoustical, or electro-magnetic. This is a result which has not been attained heretofore, in so far as the applicant is aware. Previous microphones for use in watch timing systems have been of the carbon granule type, as shown, for example, in the Norrman Patent No. 2,058,616, granted October 27, 1936, and have not beenV entirely successful. Such microphones do not give aunifor'm output because they are subject to the phenomena known as" packing, and because of the positional effects. The rst characteristic is apt to stop the operation of the system at any time, and the latter makes it necessary to frequently adjust the amplier. tofore to eliminate the effects of unwanted extraneous vibrations have not been successful either. because they have not taken intov conslderation the effectv4 of acoustical vibrations and electro-magnetic waves, and have left the microphone fully exposed to .such influences.

The improved microphone disclosed herein has I none of the defects mentioned above. The crystal element, of course, has no carbongranules to become packed, and it is absolutely.non-positional;

. that is, it operates'precisely the same regardless of the position of the microphone. `The arrangement for mountingthe microphone gives a double protection against mechanical shocks or' jars, which will be evident from the fact that the entire microphone is resiliently mounted on the v stand, While the crystal element is also resiliently mounted within the microphone casing. As regards noise interference, it may be pointed out that interference vfrom sound waves in the air is avoided by the enclosure of the crystal element in a sealed receptacle, and by the substantial enclosure of all 'the operative elements, such as the spring 60 which is inside the casing. In fact, the only part to any extent exposed Vis the end of the actuating pin 64, and that is covered by the' watch when the microphone is in use. lFinally, it will be observed that extrem care has been taken to shield the apparatus from interference by electro-magnetic or radiov waves. All metal parts of the casing and its mounting, the two outside terminals of the crystal, the actuating means for the crystal, and even'the watch being tested, are conductively connected together and to the sheath 50. These metal parts and the sheath form a complete and continuous shielding for the` live side of the microphone circuit comprising foil 36, terminal 44, and conductor 1|, all the way to the tip of the plug. At the amplifier, the `ack provided for receiving the plug is preferably shielded also and. should be provided with a shielded conductor leading from the tip spring of I The attempts that have been made here-l pense with the soldered connection between the crystal'terminal and the sheath '50, which can lbe done by bending terminal 43 down and clamping it between the lower plate 33 and the adjacent ring when the unit is assembled. 'Ihis will eiectively ground terminal 43 on the casing, which is connected to the sheath 5B through the mounting and the soldered connection at 14. The arrangeclosed ni a grounded sheath, which it mlght'be necessary to use in certain situations.

Other modifications are possible, and I do not therefore wish to be limited to the precise embodiment shown and described herein, but desire to include and have protected by Letters Patent all forms and modifications of my invention which come within the scope of the appended claims.

' I claim: l

1. In combination, a stand forming a partial enclosure and including an upright wall, a microphone, means for supporting said microphone within the enclosure and against the said wall, said means providing for rotation of the microphone relative to said enclosure and about an axis perpendicular to said wall, and means for clamping a watch to said microphone. y Y

.2. In combination, a stand including a base and a supporting member for a microphone, a microphone and casing therefor, a tubular shaft secured to said casing, a bearing member in which said shaft is rotatable, means for resiliently securing said bearing member to said supporting member, and a cord for the microphone extending through said shaft.

3. In combination, a stand, a microphone casing, means for resiliently mounting said casing on said stand, a sealed receptacle, means for mounting said receptacle in said casing, a crystal microphone element, means for resiliently mounting 'said element inside said receptacle, and means independent vof the stand, casing and receptacle for transmitting mechanical vibrations from outside the casing to said crystal element.

4. In combination, a casing including a support for a watch, a piezo electric crystal supported within-said casing, an actuator pin extending through an opening in said support so as .to be contacted by a watch resting thereon, anda mechanical coupling and said pin.'

' 5. In combination,.a casing, a piezo electric crystal mounted in said casing, a cover for said casing', a spring secured at one end to the under surface of said cover, a link connecting the other end of 1 said spring to-said crystal, a pin connected to said spring and extending upward through an opening in said 4cover so that the lend thereofmay be engaged by a watch resting on the cover.

6. In combination, a casing and cover therefor,

a piezo electric crystal mounted in said casing.'

an actuating pin extending through the cover from inside the casing, means for clamping a watch to said cover with the caseresting against the end of said pin and depressing the same, and a resilient mechanicalv coupling between said pin and crystal vwhich is operatively tensionedv by depression ofthe pin to thereafter transmit the between said crystal shocks of the watch ticks from' the watch case to the crystal.

casing having a resilient pad on its upper surface to support a watch, an actuating pin extending from the insiden of the casing through said cover and pad .and adaptedto be engaged by the case of a watch resting on the pad, and a mechanical coupling between said pin and said crystal.

8. In combination, a support for a watch, a

piezo electrical crystal, an actuating pin extending up through said support and adapted vto be depressed by a watch resting thereon, and spring coupling means betweenvsaid pin Aand crystal which is operatively' tensioned by depression' of said pin.

9. Apparatus for converting the mechanical shocks produced by the ticking of a watch into lelectrical impulses, comprising a piezo electric crystal, mechanical coupling means for transmitting vibrations from Aa watch case to said crystal, supporting-means including means for preventing the said crystal and coupling means from being influenced by extraneous shocks, and

means for preventing said crystal and couplingl means from being influenced by acoustical vibrations transmitted through the air;

-coupling means wholy shieldedirom airvibra-` Aaragon ment, a receptacle enclosing said element, an outside casing enclosing said receptacle, means for resiliently mountirigsaid element in said receptacle and said receptacle-.in said casing,

`means for supporting a watch on said casing, and 5 means forl transmitting l vibrations 4 from the watch case to said element, said last means comprising a part extending through the wall of the casing in'to engagement .with the `watch case, another part extending through the wall 4of'said 10 'receptacle and secured to said element, and;

tions by the watch and casing vfor transmitting mechanical vibrations from th'e' watch case to 10. Apparatus for converting the mechanical shocks produced by the ticking of a watch into electrical impulses, comprising a microphone,

- ratus is in usci mechanical coupling means for transmitting tick impulses from a watch case to said microphone,

phone and coupling means to shield thesame from the impact 'of sound waves in the air, with' the exception ofv a small portion oi said coupling means which is in contact with a watch case and is completely shielded 11. Apparatus for converting'the 'mechanical shocks produced by the ticking of awatch into electrical impulses and for conducting said impulses to an ampliiier, comprising a microphone, a metallic casing surrounding said microphone, mechanical coupling means for transmitting vibrations from a watch Acase outside the casing ,to said microphone, said coupling means being conductively connected to said casing, mounting means for said casing including a metallic conduit conductively connected thereto, a conductor extending from the microphone through said conduit and'beyond the end thereof, a metallic shieldv surrounding the conductor outside Athe 'conduit and .extending also inside the conduit,

plug for completely shielding the microphone to plug circuit from electro-magnetic waves, a connection between the other terminal of said -microphone and. the shielding, and means for thereby when the appa- .for a watch, means for temporarily securing a said` element.

15. In combination, a crystal .microphone el'e-- ment, a metallic casing surrounding said elementjg* and in which said element is supported,4 coupling means located inside said casing but including a part projecting through` the wall-thereof to engage a watch supported on said casing, and circuit means for. grounding said casing, said'cou- 30 'pling means including'the part in contact with.

the watch A.being of metal and being connected to the casing, whereby said coupling means and said watch arealso grounded.

16. In combination, 'a casing, a-piezo-electric .35 crystal supported within said casing, a support vWatch to said support, bearing means 4in which the suppQt lsmounted-for rotation to enable the watch secured thereto tobe moved todierent positions, an actuator pin extending through an opening Vin saidsupportso as to be contactedby said watchfaid a mechanical'coupling between said crystal and said pin.

17.'In combination, a casing, a piezo-electric crystal supported in said casing, a support for a watch, means for temporarily securing a watch to said support, re'silient means interposed between said watch and4 support, an actuator pin extendingthrough' an opening in said support so as to bev contacted by-the said watch, and a mechanicalcoupling between said crystal and said pin.

transmitting mechanical vibrations from outside the casing to said microphone.A

13. In combinationpa crystalrmicrophone-elei means comprising a casing for said microphone,

18. A microphone pick-up device` for use in watch testing, comprising 'a microphone element having two terminals,- a-plug a flexible conductor extendingA from one terminal-of said microphone-.to a conductor of said plug, means f or completely shielding Athe microphone to plug circuit from extraneous electrical 'inuencea said 'rHoMAs i3. 

